RESUSCITATION OF CONTROLLED HEMORRHAGIC SHOCK IN HYPERTENSIVE AND NORMOTENSIVE RAT MODELS: THE EFFECTS OF HYPERTONIC-HYPERONCOTIC SOLUTIONS

Introduction. Recently there has been increased hypertonic and hypertonic-hyperoncotic solutions for the initial resuscitation of hemorrhagic shock. Since compensatory mechanisms during hemorrhagic shock in hypertensive patients is different from normotensives, the objectives of this project was studing the therapeutic effects of these solutions on resuscitation of controlled hemorrhagic shock in hypertensive and normotensive rats. Methods. 39 rats were randomized in two groups: control and hypertensive groups. To obtain hypertensive animals, the rats received desoxycorticosterone acetate (DOCA) [10 mg/kg, twice/week] 3 weeks before the experiment. Then all rats were anesthetized and were subjected to hemorrhage until mean blood pressure was reached to 40-50 mmHg and maintained for 30 minutes. Then animals resuscitated in each group with either: 1) Hypertonic (HT) or 4 cc/kg 5 percent NaCI. 2) Large volume isotonic (LV) or 22 cc/kg normal saline. 3) Hypertonic Hyperoncotic (HTIHOC) or 4 cc/kg 20 percent NaCI and 20 percent serum albumin; 3: 1v/v. 4) Small volume isotonic (SV) or 4cc/kg normal saline. All animals were monitored 1 hour after infusion. Blood pressure, electrolyte and osmolality was measured in each subgroup and group after resuscitation. Finally all animals were sacrified and brain water content was measured. Results. Before hemorrhage, systolic and mean arterial blood pressure (MAP) in hypertensive rats (149.5±3.80, 119.44±3.23 mmHg) were significantly higher than normotensive rats (131. 70±4.14, 108.11±3.31 mmHg) (P<0.05).HT/HOC resuscitation was associated with pronounced improvement in MAP in hypertensive rats during 1h after resuscitation. Serum osmolality was significantly different between subgroups in control group 1h after resuscitation (P ≤ 0.05).(HT subgroup osmolality was different from SV subgroup). The comparsion between similar subgroups of two groups indicates significant difference of osmolality in SV subgroup (P < 0.05). No significant difference was observed in other variables before hemorrhage and after resuscitation between four subgroups in each group and between similar subgroups in two groups of hypertensive and normotensive. Discussion. HT/HOC resuscitation leads to increased MAP after controlled hemorrhagic shock in hypertensive rats, but there were not any significant difference in HT,LV,HT/HOC and SV solutions in control group. This difference may be attributed to increased vascular permeability in hypertension. Increased osmolality in HT subgroup in control group can be attributed to high osmolality of hypertonic solutions.